1. Field of the Invention
This invention relates to a method of metering an air-gap in an electric rotating machine such as a generator for use in vehicles.
2. Description of Prior Art
Generally, electric rotating machines such as a generator for use in vehicles, e.g., cars include those which comprise a rotor core provided integrally on a rotary shaft and an open-type stator core which has an exposed outer periphery and is arranged coaxially with the rotor core around the outer periphery thereof as described in, for example, U.S. Pat. Nos. 4,488,070 and 4,419,597, and there is formed an air-gap of an appropriate width between the inner periphery of the stator core and the outer periphery of the rotor core in order to avoid the contact between the rotor core and the stator core while the former rotates. It is preferred to make the width of the air-gap as small as possible in order to obtain a high output electric rotating machine. However, when it is attempted to reduce the air-gap with view to rendering the machine high outputting the air-gap cannot be reduced too much in view of deviations encountered upon assembling the stator core and rotor core of dimensional tolerance or deformation of the rotor core which would occur due to high speed rotation. Heretofore, no measurement of air-gaps has been made for each article or generator, with the result that the precision of the measurement is poor. It has conventionally been adopted to set up an air-gap size which can sufficiently clear the allowance or dimensional tolerance large enough to be applicable to all the articles produced on a large scale which has been determined taking into consideration the above-described deviation in each article. As a result, air-gaps cannot but help being set up at an excessively large value since reduction in the air-gap could affect the reliability of the articles produced because the rotor core would otherwise contact the stator core due to deviation, deformation, etc. Needs for high output rotating machines, particularly generators, are not met satisfactorily and some improvements are desired.